Liquid crystal display devices have been widely used. For example, a liquid crystal display module can be applied to a screen of an electronic product, such as a television, a tablet, a notebook computer, a desktop, a mobile phone and so on. Each display module includes a backlight panel. Generally, a number of LED strings are uniformly placed in the backlight panel and each LED string includes light-emitting diodes (LEDs) having high brightness. In addition, each display module includes an LED short-circuit detector circuit for detecting a short circuit or other abnormal states occurring in each LED string. However, the LED short-circuit protector circuit has complex structure and requires high costs, and cannot timely protect the LED string.